A transportation system called an intelligent transport system (ITS) is known as a transportation system for operating transportation such as automobiles or trains, and studies on high-functional high-speed ITSs have been conducted. Particularly, in an ITS, implementation of a so-called vehicle-to-X (V2X) communication function such as between vehicles (vehicle-to-vehicle (V2V)) or between a vehicle and infrastructure (vehicle-to-infrastructure (V2I)) is under review, and connection by wireless communication is more desirable in consideration of mobility of vehicles.